A thin film transistor substrate constituting a display panel of an active matrix drive type includes a thin film transistor (hereinafter referred to as a “TFT”) serving as a switching element in each pixel which is the smallest unit of an image.
A bottom gate-type TFT includes a gate electrode provided on an insulating substrate, a gate insulating film provided to cover the gate electrode, an island-shaped semiconductor layer provided on the gate insulating film to overlap the gate electrode, and a source electrode and a drain electrode provided on the semiconductor layer to overlap the gate electrode, and to be spaced from each other.
For example, Patent Document 1 discloses that, in an inverted staggered (bottom gate-type) amorphous silicon TFT, an intrinsic amorphous silicon film is altered by a plasma process, thereby improving reliability of the TFT.